1. Field of the Invention
The present invention relates to a clutch engaging and disengaging apparatus. More specifically, the present invention relates to a clutch engaging and disengaging apparatus that engages and disengages a clutch by utilizing the rotation of a driving mechanism.
2. Background Information
Among clutch engaging and disengaging apparatuses for vehicle clutches, there are apparatuses that operate a clutch by using the rotation of a motor (i.e., driving mechanism) to produce hydraulic pressure and to transmit the hydraulic pressure to a slave cylinder.
Examples of this type of clutch engaging and disengaging apparatus are the devices presented in Laid-Open Japanese Patent Publication No. 10-119603 and Laid-Open Japanese Patent Publication No. 11-201188. These clutch engaging and disengaging apparatuses are provided with a driving mechanism, a motion converting mechanism, a hydraulic mechanism, and a load storing mechanism. The driving mechanism has a motor that generates torque. The motion converting mechanism converts the rotational motion of the motor into a linear motion. The hydraulic mechanism uses the linear motion of the motion converting mechanism to produce hydraulic pressure and engage or disengage the clutch. The load storing mechanism has a coil spring that stores a load when the motion converting mechanism moves linearly in one direction and releases the stored load when the motion converting mechanism moves linearly in the opposite direction. The motion converting mechanism is provided with a reduction mechanism and a push rod. The reduction mechanism has a worm gear that is rotated by the motor and a worm wheel that meshes with the worm gear. The push rod moves linearly in response to the rotation of the worm wheel. The hydraulic mechanism is provided with a master cylinder that produces hydraulic pressure and a tandem cylinder that transfers the hydraulic pressure generated in the master cylinder to a slave cylinder. The master cylinder is provided with a piston that is pushed by one end of the push rod.
With this type of clutch engaging and disengaging apparatus, the motor is rotated in the reverse (or forward) direction to engage the clutch. When this is done, the motion converting mechanism moves linearly in one direction and the coil spring of the load storing mechanism stores the load as an elastic force. Since the push rod does not push the piston, the master cylinder does not produce hydraulic pressure and the clutch engages. Conversely, the motor is rotated in the forward (or reverse) direction to disengage the clutch. When this is done, the motion converting mechanism moves linearly in the opposite direction and causes the push rod to push the piston. Here, the coil spring of the load storing mechanism releases the load it stored as an elastic force when the motor rotates in the reverse (or forward) direction and assists in causing the push rod to push the piston. As a result, hydraulic pressure is produced in the master cylinder and the clutch disengages.
In the clutch engaging and disengaging apparatuses just described, the radially outside portion of the coil spring of the load storing mechanism is supported by a guide member such that it can extend and contract in a straight manner with respect to the direction in which the load is stored and released. Consequently, the number of parts making up the load storing mechanism is relatively large.
Also, the linkage part between the push rod and the worm wheel swings in response to the rotation of the worm wheel. This swinging motion causes the end of the push rod to move linearly with respect to the piston. The push rod is not always straight with respect to the direction in which it pushes the piston and, consequently, the end of the push rod touches against the piston at a slant due to the swing motion of the linkage part between the push rod and the worm wheel. Thus, in addition to the load in the direction in which the piston is being pushed, another load also acts on the piston in a direction perpendicular to the pushing direction. As a result, the lateral surfaces of the piston undergo wear.
In view of the above, there exists a need for a clutch engaging and disengaging apparatus which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.
An object of the present invention is to reduce the number of parts in a clutch engaging and disengaging apparatus that engages and disengages a clutch using the rotation of a driving mechanism. Another object is to reduce piston wear in a clutch engaging and disengaging apparatus that engages and disengages a clutch using the rotation of a driving mechanism.
In accordance with a first aspect of the present invention a clutch engaging and disengaging apparatus that engages and disengages a clutch using the rotation of a driving mechanism is provided. The apparatus has a motion converting mechanism, a load storing mechanism, and a hydraulic mechanism. The motion converting mechanism converts the rotational motion of the driving mechanism into linear motion. The load storing mechanism stores a load when the motion converting mechanism moves linearly in one direction and releases the stored load when the motion converting mechanism moves linearly in the opposite direction. The hydraulic mechanism uses the linear motion of the motion converting mechanism to produce hydraulic pressure and engage or disengage the clutch. The load storing mechanism has a spring that is connected to the motion converting mechanism and can extend and contract in response to the linear motion of the motion converting mechanism. Further, the load storing mechanism has a support member that supports an axially facing end part of the spring.
With this clutch engaging and disengaging apparatus, an axially facing end of the spring of the load storing mechanism is supported by a support member but the axially facing end is not supported in a direction perpendicular to the direction in which the spring extends and contracts. In short, the guide member used in conventional load storing mechanisms to support the radially outside portion of the spring in directions perpendicular to the extension and contraction directions has been omitted. As a result, the number of parts making up the clutch engaging and disengaging apparatus can be reduced.
A clutch engaging and disengaging apparatus in accordance with a second aspect of the present invention is the apparatus of the first aspect, wherein the motion converting mechanism has a reduction mechanism that reduces the speed of the rotational motion of the driving mechanism and a push rod that receives a load transmitted from the reduction mechanism. The hydraulic mechanism has a piston that is pushed by one end of the push rod.
A clutch engaging and disengaging apparatus in accordance with a third aspect of the present invention is the apparatus of the second aspect, wherein the spring is arranged such that when one end of the push rod pushes the piston, the spring can apply a canceling load that can cancel out a load acting at the one end in a direction perpendicular to the direction in which the piston is pushed.
With this clutch engaging and disengaging apparatus, the rotation of the driving mechanism is converted into linear motion by the motion converting mechanism and the piston is pushed by one end of the push rod of the motion converting mechanism. A linkage part between the push rod and the reduction mechanism swings. The swinging motion causes the one end of the push rod to move linearly with respect to the piston. The push rod is not always straight with respect to the direction in which it pushes the piston and, consequently, the end of the push rod touches against the piston at a slant due to the swing motion of the linkage part between the push rod and the worm wheel. Thus, in addition to the load in the direction in which the piston is being pushed, another load also acts on the piston in a direction perpendicular to the pushing direction. This aspect is similar to that in conventional clutch engaging and disengaging apparatuses, but in the present invention the spring of the load storing mechanism is arranged such that when one end of the push rod pushes the piston, the spring can apply a canceling load that can cancel out a load acting at the one end in a direction perpendicular to the direction in which the piston is pushed. Consequently, loads applied from the push rod to the piston in a direction perpendicular to the direction in which the piston is being pushed are reduced. Therefore, piston wear can be reduced.
A clutch engaging and disengaging apparatus in accordance with a fourth aspect of the present invention is the apparatus of the second or third aspect, wherein the spring is supported by the other end of the push rod and is arranged on the opposite side of the push rod relative to the piston. Thus, the spring can push the other end toward the piston.
With this clutch engaging and disengaging apparatus, the spring of the load storing mechanism can be extended and contracted along the same direction as the direction in which the push rod pushes the piston. Consequently, when the push rod pushes the piston, the load stored in the spring can be released smoothly.
A clutch engaging and disengaging apparatus in accordance with a fifth aspect of the present invention is the apparatus of any of the second to fourth aspects, wherein the reduction mechanism has a worm gear that is rotated by the driving mechanism and a worm wheel that meshes with the worm gear.
With this clutch engaging and disengaging apparatus, the rotational motion of the driving mechanism is transmitted to the push rod using a reduction mechanism having a worm gear and a worm wheel. Consequently, even if the driving mechanism stops and an opposing torque is imparted to the worm wheel from the hydraulic mechanism and the load storing mechanism, the worm wheel will remain locked due to its meshing with the worm gear and the position of the push rod can be maintained.
These and other objects, features, aspects, and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention.